The tiny, bright orange mites that we know as harvest mites are classed in two species that cause problems in both dogs and cats: Neotrombicula (syn. Trombicula) autumnalis and Straelensia cynotis. They are responsible for a condition called Trombiculosis
The infestation can cause itchy, red, inflamed skin, between toes, usually affecting the feet, legs, armpits, genitals, tummy, and can occasionally affect the ears(most commonly in cats).
Harvest mites will attach to your pet while walking in grassy areas, woodlands, most active between July and November. The mites will attach to any animal that passes by. Infestated or allergic animals will have intensely itchy, red, inflamed skin in the areas they’ve been bitten.
The adult mites lay their eggs in decomposing vegetation.A few days later the eggs hatch into larvae(orange coloured, 0.2–0.3 mm in length). The larvae are usually the parasitic stage. Larvae become active in dry, sunny conditions at temperatures exceeding +16°C. The term “harvest mite” is given due to the vegetation it lives on.
Harvest mites do not transfer from animal to animal. After attaching themselves to their hosts they feed for 5 to 7 days. Thereafter, they detach and continue their development as free-living stages on the ground. The life cycle may take 50–70 days or more to complete. Harvest mites are resistant to adverse climatic conditions and female mites can live for more than 1 year.
The diagnosis is made by clinical observation of the mites, corelated with the time of year and the history of affected dogs and cats. Usually owners live in the countryside, with their pets frequently visiting woodlands or tall grass. The larval mites can be seen fairly easily without magnification.
Harvest mites are found in ground–skin contact areas like the head, ears, feet, and abdomen. The infestation can be highly pruritic. With the naked eye they look pretty peculiar due to their bright orange appearance, usually seen in high numbers. The pet can become highly sensitive if repeated infestation.
Control of trombiculosis is difficult due to the fact that reinfestations are frequent in animals exposed to these mites. Regular use of spot on solution might be the key to stop the harvest mite finding it’s attractive host.
It is important that you search the help of your veterinarian if you suspect harvest mites.
The vet will usually choose to use a spray containing fipronil, commonly re-applied in 5-7 days in the areas where the harvest mites are present. Removal or mites is recommended if safe to do so.
If the skin is affected or your pet becomes very itchy, the vet might choose anti-inflammatory medication to alleviate the symptoms. If heavy infestation is present, then skin infections might be present, needing further treatment.